From bdfea7f41fb2d390d564676addd9242289990a85 Mon Sep 17 00:00:00 2001
From: Jonathan Kew <jkew@mozilla.com>
Date: Wed, 18 Sep 2013 11:48:38 +0100
Subject: [PATCH] Bug 838105 - don't rely on key lookup to remove items from
 the user font cache, as the principal could have changed. r=jdaggett

---
 gfx/thebes/gfxUserFontSet.cpp | 18 +++++++++++++-----
 gfx/thebes/gfxUserFontSet.h   |  1 +
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/gfx/thebes/gfxUserFontSet.cpp b/gfx/thebes/gfxUserFontSet.cpp
index c02a5c943da2..1b461d3e08f6 100644
--- a/gfx/thebes/gfxUserFontSet.cpp
+++ b/gfx/thebes/gfxUserFontSet.cpp
@@ -810,6 +810,14 @@ gfxUserFontSet::UserFontCache::Entry::RemoveIfPrivate(Entry* aEntry,
     return aEntry->mPrivate ? PL_DHASH_REMOVE : PL_DHASH_NEXT;
 }
 
+PLDHashOperator
+gfxUserFontSet::UserFontCache::Entry::RemoveIfMatches(Entry* aEntry,
+                                                      void* aUserData)
+{
+    return aEntry->GetFontEntry() == static_cast<gfxFontEntry*>(aUserData) ?
+        PL_DHASH_REMOVE : PL_DHASH_NEXT;
+}
+
 PLDHashOperator
 gfxUserFontSet::UserFontCache::Entry::DisconnectSVG(Entry* aEntry,
                                                     void* aUserData)
@@ -902,11 +910,11 @@ gfxUserFontSet::UserFontCache::ForgetFont(gfxFontEntry *aFontEntry)
         return;
     }
 
-    gfxUserFontData *data = aFontEntry->mUserFontData;
-    if (data) {
-        sUserFonts->RemoveEntry(Key(data->mURI, data->mPrincipal, aFontEntry,
-                                    data->mPrivate));
-    }
+    // We can't simply use RemoveEntry here because it's possible the principal
+    // may have changed since the font was cached, in which case the lookup
+    // would no longer find the entry (bug 838105).
+    sUserFonts->EnumerateEntries(
+        gfxUserFontSet::UserFontCache::Entry::RemoveIfMatches, aFontEntry);
 }
 
 gfxFontEntry*
diff --git a/gfx/thebes/gfxUserFontSet.h b/gfx/thebes/gfxUserFontSet.h
index 6395505dca2c..40ad9fb5ac2e 100644
--- a/gfx/thebes/gfxUserFontSet.h
+++ b/gfx/thebes/gfxUserFontSet.h
@@ -346,6 +346,7 @@ public:
             gfxFontEntry* GetFontEntry() const { return mFontEntry; }
 
             static PLDHashOperator RemoveIfPrivate(Entry* aEntry, void* aUserData);
+            static PLDHashOperator RemoveIfMatches(Entry* aEntry, void* aUserData);
             static PLDHashOperator DisconnectSVG(Entry* aEntry, void* aUserData);
 
         private: